textproduct: Albany

WHAT HAS CHANGED

Lowered POPs slightly for Thursday compared to NBM due to best forcing still being off to the west.

Similar to past few forecasts, have lowered daytime temps slightly for Wed-Fri from NBM values. Still, combination of heat and humidity will have heat index values in valley areas approaching or exceeding Heat Advisory criteria, especially for Friday.

KEY MESSAGES

1) Above normal temperatures and increasing humidity levels are expected through Friday. Heat Index values may be high enough to allow for an increased risk in heat related illnesses on Thursday and Friday.

2) There is a chance for thunderstorms each day Wednesday through Friday, mainly in the afternoon and evening hours. Some storms could be severe with damaging winds, especially on Friday. Storms may be capable of producing heavy downpours as well.

DISCUSSION

KEY MESSAGE 1...

A warm and humid air mass will be building over the region for the next few days, as surface high pressure shifts eastward and a low level southerly flow will remain in place over the area. 850 hpa temps will be warming to +16 to +19 C across the entire region ahead of an approaching storm system.

With a warm front moving through the area, there will be some clouds, showers and possible thunderstorms on Wednesday. This may limit daytime heating slightly for Wednesday, but valley areas should still reach into the lower 80s. With dewpoints rising through the 60s, this should still keep heat index values in the lower to middle 80s for valley areas.

Even warmer temps are expected for Thursday and Friday, with a partly to mostly sunny sky both days, despite some late day convection once again. Highs will be in the upper 80s to near 90 on Thursday and probably in the lower 90s for Friday. With dewpoints nearing 70 degrees in valley areas, heat index values will be in the 90s both days. Heat index values may reach advisory criteria in the mid Hudson Valley for Thursday and many valley areas for Friday. These values will allow for an increased risk for heat related illnesses each day.

Somewhat cooler and less humid conditions are expected behind a cold front for the weekend, so this will lower the threat for heat-related illnesses by Saturday.

KEY MESSAGE 2...

There will be the potential for convection each day, beginning Wednesday through Friday. While there could be a threat for severe storms each day, the most widespread threat will probably be on Friday due to better forcing over the region.

On Wednesday, an upper level disturbance and surface warm front will be moving across the area. Widespread clouds are expected through the day, which may limit surface heating and overall instability. There will be some passing showers and rumble of thunder around midday before another round of convection for the afternoon and evening. These earlier showers and clouds may keep lapse rates on the low side as well (under 6 deg C/km). The overall forcing aloft is rather weak and 0-6 km bulk shear values are generally in the 20-25 kt range. 12z SPC HREF shows the best updraft helicity just southwest of the area, but it is fairly close. Overall, the severe threat is fairly low for Wednesday, with a better threat off to the west of the area. SPC has the marginal risk scrapping into our western areas. While an isolated storm late in the day may have damaging wind gusts, the overall threat is fairly low for Wednesday. With the rising PWATs, locally heavy downpours may be a concern.

For Thursday, forcing still remain low, but there should be better instability compared to Wednesday due to more sun and higher heating. The main forcing is still far off to the west, so overall coverage of storms looks on the lower side and shear is still fairly low. Still, if storms can get going, there may be a threat for isolated damaging winds. There remains a marginal risk once again for severe storms, but the higher threat will again be west of the area.

Higher coverage of thunderstorms looks to occur for Friday, for the afternoon into the evening, as the main upper level forcing gets closer and a surface cold front approaches from the west. There may be an organized line of thunderstorms for late in the day. Lapse rates aloft for Friday look a little more impressive compared to Wed/Thurs. SPC has a Day 4 outlook with a 15% contour (SLIGHT risk equivalent) over our area due to the decent lapse rates and moist dewpoints in place. Will continue to monitor model trends, as the timing of the boundary will determine the overall severe risk for Friday.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Through 18Z Wednesday... VFR conditions will prevail for the majority of this TAF period. FEW-SCT high clouds will dominate this afternoon/evening along with some mid-level fair weather cumulus, with more mid-level clouds expected to develop throughout the overnight hours at all terminals. KGFL could see periods of mist/fog overnight as surface dew points start to increase, reflected by TEMPO groups. Showers are expected to begin moving into the region tomorrow morning between 10Z-14Z, though no impacts are expected in regards to vis. Cigs dropping to MVFR during periods of rain are not out of the question, but confidence is low at this time and will likely increase with future TAFs.

Southerly-southwesterly winds are starting off this TAF period, with some moderate gusts present at KPOU this afternoon. Winds are expected to subside after sunset tonight, becoming light and variable at KGFL and KPSF, while still remaining out of the south at KALB and KPOU. Winds are expected to strengthen again tomorrow as the aforementioned showers move into the region, coming out of the south-southwest to southeast through the end of the TAF period.

Outlook...

Wednesday Night: High Operational Impact. Likely SHRA...TSRA. Thursday: High Operational Impact. Chance of SHRA...TSRA. Thursday Night: Moderate Operational Impact. Slight Chance of SHRA...TSRA. Friday: Moderate Operational Impact. Likely SHRA...TSRA. Friday Night: High Operational Impact. Likely SHRA...TSRA. Saturday: Low Operational Impact. Breezy. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Low Operational Impact. Slight Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.